Printing apparatus

ABSTRACT

A printing apparatus of the type having an image carrier, a color carrier, a font with a plurality of raised, selectively positionable characters, and a piston assembly whereby activation of the piston assembly causes an image to be transferred from the color carrier to the image carrier. The printing apparatus further includes backspace means for compensating for letter interlock.

I United States Patent 91 1 3,834,50 Bradshaw Sept. 10, 1974 PRINTINGAPPARATUS 324853315 13/1133; [75] Inventor: Franklin C. Bradshaw, St.Paul, 4;]973 Mum. 3,753,482 8/1973 [73] Assignee: Kroy Industries Inc.,Stillwater,

Minn. Primary Examiner-Robert E. Pulfrey Assistant Examiner-R. T. Rader[22] Frled: Jan. 30, 1973 Attorney, Agent, or Firm-Dorsey, Marquart, 21APPL 327 945 Windhorst, West & Halladay [52] US. Cl 197/6.7, 197/82,197/91 [57]. ABS CT [51] Int. CL i B41 j 1/30 A prlntmg apparatus of thetype havmg an image car- [58] Field 7 rier, a color carrier, a font witha plurality of raised,

l97/l8 84 84 A 84 B selectively positionable characters, and a pistonassembly whereby activation of the piston assembly [56] References Citedcauses an image to be transferred from the color carrier to the imagecarrier. The printing apparatus fur- UNITED STATES PATENTS ther includesbackspace means for compensating for Brown letter interlock 3,384,2165/1968 Thayer 197/18 3,391,773 7/1968 Nicole et al. l97/6.7 8 Clalms, 15Drawing Figures i j i E .llllllllllllll! PAIENTEBSEPIOW 3.834.507

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SHEET 2 OF 5 PRINTING APPARATUS BACKGROUND AND SUMMARY OF THE INVENTIONThe present invention relates generally to the field of lettering andprinting equipment and more specifically to a printing apparatusdesigned for high quality, ap propriately spaced printing of charactersonto an image carrier with means for compensating for letterinterlocking.

In the past, lettering such as that appearing on engineering drawingsand the like has been hand lettered either by free hand or through theuse of mechanical lettering aids such as those commonly identified bythe trademark LeROY and manufactured by Kueffel & Esser Company ofMorristown, New Jersey. Because it was desired that this lettering beuniform and of high quality, the skill of a trained draftsman was, ofcourse, required. As a result these conventional methods were quiteexpensive, not only because of the skilled draftsman which wasnecessary, but also because such lettering when done free hand or withthe use of lettering aids was quite time consuming. Thus, there was, and

still is, a real need for a printing apparatus which can be used toaccomplish the high quality, appropriately spaced lettering desired forengineering drawings and the like and which can be used by a relativelyunskilled operator.

One of the features which such an apparatus must have in order to beacceptable is a means for adjusting the position of the printing surfaceto compensate for letter interlocking. Letter interlocking, as it isreferred to in the present application is the ability of certain lettercombinations to interlock or appear improperly spaced because of theparticular shape of such letters. For example, the letters A and V or Aand W if printed as adjacent characters would appear improp- DESCRIPTIONOF THE DRAWINGS FIG. 1 is a perspective view of the exterior features ofthe lettering apparatus of the present invention.

FIG. 2 is a top perspective view of the lettering apparatus of thepresent invention.

FIG. 3 is a perspective, exploded view of the internal elements of thepresent invention.

FIG. 4 is a plan view showing, among other things, the travel of theimage carrier through the apparatus and the means for advancing theimage carrier during the printing cycle.

FIG. 5 is a plan view showing the travel of, among other things, thecolor carrier through the apparatus and the means for advancing thecolor carrier during the printing cycle.

FIG. 6 is a close-up view, partially in section, of the means foradvancing the image carrier.

FIG. 7 is a close-up view of the means for compensating for letterinterlocking.

FIG. 8 is a close-up view, partially in section, of a portion of themeans for varying the force propelling the piston head upwardly towardthe raised character in proportion to the square area of the characterbeing printed.

FIG. 9 is a plan view of one side of the cam assembly.

FIG. 10 is a front view of the cam assembly.

FIG. 1 1 is a close-up view, partially in section, of the means foractivating the printing cycle and insuring proper alignment of theraised character prior to activation.

FIG. 12 is a plan view of the font.

FIG. 13 is a side view, partially in section, of the font.

FIG. 14 is a view, partially in section, of the piston assembly and aportion of the means for varying the force propelling the piston headtoward the raised character.

FIG. 15 is a view, partially in section, of the piston assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference first to FIGS. 1and 2, the printing or lettering apparatus of the present inventionincludes an external shell 8 covering the frame of the apparatus whichis not specifically shown but which is disposed throughout the apparatusfor supporting the shell 8 and various shafts, slides, springs and otherelements of the apparatus as will hereinafter be described.

Generally, a font 36 (individually illustrated in FIGS. 12 and 13) ispositioned on the shell 8, as shown, by means which permit the font 36to be free spinning or freely rotatable about a center shaft 13extending upwardly from the surface of the shell 8. As shown in FIGS. 12and 13, a plurality of raised characters 27 are disposed on theunderside of the font 36 near its periphery so that as the font 36 isrotated about the shaft 13, the characters 27 pass a printing station 55(FIGS. 1 and 2) positioned immediately above a piston assembly. A fontretainer 9 adapted for limited slideable movement relative to the shell8 is positioned such that a portion of the retainer 9 extends over theperiphery of the font 36 in the area of the printing station 55 to serveas a means against which the font 36 may be supported during theprinting cycle tooppose the upward movement of a portion of the pistonassembly against the underside of the font 36 and to oppose movement ofthe font 36 in response to movement of analignment means hereinafterdescribed.

An image carrier or print media and a color carrier or ribbon areadapted for movement past the printing station 55 at right angles toeach other between the raised character on the underside of thefont 36andthe piston assembly so that when the piston is released and caused tomove upwardly toward the font 36, an image of the raised character istransferred from the color carrier to the image carrier. It should alsobe noted that A the image carrier passes the center of the font 36during its advancement and printing is done on a center line of the font36. As further illustrated in FIGS. 1 and 2, the shell 8 contains anumber of external buttons and selector wheels which control theoperation of the lettering apparatus. In this respect, a print button 28operates to activate a motor and commence the printing cycle, a wordspace button 82 serves to advance the image carrier an appropriateamount between adjacent words, a lettering spacing selector wheel 63functions to adjust the amount of the image carrier which is ad vancedbetween each printed character, a tape advance button 94 operates toadvance the image carrier when relatively large advancement is desiredand to allow proper cut-off length, a letter interlock button 142 servesto physically backspace the image carrier a specified amount to obtainproper spacings for certain combinations of letters and to compensatefor letter interlocking, a font size selector wheel 124 functions toprovide for proper ribbon spacing, letter spacing and letter interlockspacing corresponding to the character size of a particular font, andthe button 83 operates to cut the image carrier for removal from theapparatus when such is desired.

The internal elements of the lettering apparatus can be seen best withreference to FIG. 3. As shown, the apparatus is driven by a motor havinga shaft 12 upon which is mounted an anti-reverse clutch 11 designed,among other things, to permit revolution of the clutch, and thus a camassembly 14 secured to it, in one direction only. The motor 10 is aconventional skeleton frame motor which, in the preferred embodiment, isa Model No. PF 4515U12I supplied by Merkle-Korff Gear Co. of FranklinPark, Illinois. As illustrated, the clutch 11 is mounted to the shaft 12and together with a single revolution clutch assembly 15, serves as arotatable support for the cam assembly 14 during the printing cycle. Aswill be described in more detail throughout the specification and withreference to other Figures, the cam assembly 14 has four cam surfaceswhich, during a single revolution, drive a piston assembly 49, a meansfor advancing the print media and a means for advancing the colorcarrier, and serve to insure proper alignment of the character beingprinted. The single revolution clutch 15 is a relatively cylindricalelement disposed between the clutch 11 and the cam assembly 14 and hasmeans designed to limit the cam assembly 14 and also the motor 10 tosingle revolution during a printing cycle.

A catch 16 is integrally formed with the clutch 15 and extends outwardlytherefrom for engagement with one end of an elongated member 18 of atrigger assembly 19. As illustrated, the member 18 is bifurcated at oneend for operative engagement with a trigger stem 20 and a trigger stemconnection 21 and is pivotally connected between its ends at the pivot22 to the frame of the apparatus. The end of the member 18 adapted forengagement with the catch 16 includes a cut-out portion 25 designed tofit over the catch 16 and a latch 24 designed to engage the catch 16 tolimit the rotational movement of the clutch 15 and thus the entire camassembly 14.

The trigger stem connection 21 which is rigidly secured to the triggerstem-20 includes a transversely ex tending pin 26 adapted to fit betweenthe bifurcated portions of the member 18 for transferring reciprocalmovement of the stem 20 to the member 18, thereby causing the member 18to pivot about its pivot 22. The trigger stem 20 extends upwardly fromthe connection 21, through one end of a bracket 29 and is connected witha print button 28 at its upper end. The bracket 29,

is pivotally connected to the frame of the apparatus at the pivot 30 andhas one end operatively connected with the trigger assembly 19 fortransferring reciprocal movement of the stem 20 to a pair of alignmentpins or font locking pins 31, 31. The reciprocal movement of the stem 20is transferred to the bracket 29 by a washer 32 rigidly secured to thestem 20 immediately above the point at which the stem 20 passes throughan elongated opening in the bracket 29. When the button 28 is depressedthe bracket 29 pivots in a counterclockwise direction about the pivot 30as a result of engagement with the washer 32. It should be noted thatthe opening in the bracket 29 must be elongated to compensate for thepivotal movement of the bracket 29 and the reciprocal movement of thestem 20.

The other end of the bracket 29 is rigidly connected with a pin supportmember 34 which supports a pair of upstanding font locking pins 31, 31.As illustrated best in FIG. 11, the pair of pins 31, 31 are tapered attheir upper ends and are adapted to fit into corresponding taperednotches 35 in the underside of the printing font 36 which appropriatelypositioned to insure proper alignment of the character to be printed,and thus the font 36, during the printing cycle. The pins 31, 31 extendthrough a pair of conventional spring members 38, 38 which abut aportion of the apparatus frame 39 and which serve to continuously biasthe support member 34, and thus the pins 31, 31, downwardly as viewed inFIG. 11. This force on the member 34, and thus the bracket 29, opposesdepression of the print button 28 (FIG. 3) A microswitch, illustrated inFIG. 11 by the reference numeral 40, has a switch member 41 connected tothe pin support member 34 in such a manner that the upward movement ofthe support 34 and the pins 31, 31 into the corresponding notches 35activates the switch 40 which in turn activates the motor 10 (FIG. 3).It should be noted that the switch 40 is positioned such that it will beactivated only when the pins 31, 31 are fully extended into the notches35. This insures proper alignment of the font 36 upon commencement ofthe printing cycle. For example, if the font 36 is manually positionedso that the pins 31, 31 engage a portion of the font 36 between thenotches 35, the switch 40, and thus the motor 10 (FIG. 3) will not beactivated when the print button 28 is depressed since the pins 31, 31will not have moved a distance sufficient to trigger such activation. Ifthe font 36 is positioned so that the pins 31, 31, although notperfectly aligned, have their upper tapered points disposed anywhere inthe notches 35, proper alignment will be achieved as a result of thewedging action between the opposing tapered surfaces of the tips of thepins 31, 31 and their respective notches 35 and the upward movement ofthe pins 31, 31. For example, if the font 36, as viewed in FIG. 1 1,were misaligned slightly to the right, upward movement of the pins 31,31 upon depression of the print button 28 would cause the free spinningfont 36 to be moved slightly to the left, thereby achieving properalignment prior to commencement of the printing cycle. It should benoted that the font retainer 9 shown best in FIGS. 1, 2 and 14 has aportion extending over the periphery of the font 36 to oppose upwardmovement of the font 36 and to allow for the above mentioned wedgingaction to occur. Thus, it can be seen that the above discussed elementsprovide a means for properly aligning the character to be printed andinsuring such proper alignment upon commencement of the printing cycle.

With general reference to FIG. 3 and specific reference to FIGS. 4, 5, 9and 10, it can be seen that the cam assembly 14 has four cam surfaces42, 45, 48 and 50 which function to drive the apparatus of the presentinvention during a single revolution of the cam 14. First, the camsurface 42, best shown in FIGS. 3 and 4, is located at the outermostperiphery of the assembly 14 and functions to drive the image carrieradvance mechanism. Second, the cam surface 45, best shown in FIGS. 3, 5and 10, is disposed on one side of the assembly 14 and drives the colorcarrier advance mechanism indicated generally in FIG. 5 by referencenumeral 46. Third, the cam surface 48, which is an interior surfaceillustrated best in FIGS. 3, 9, l4 and 15, drives the piston assembly49. The operation of each of these surfaces and the elements which theydrive will be described in more detail later in the specification.

Finally, the cam surface 50, illustrated best in FIGS.

3 and 4, comprises a partially cylindrical surface and serves to lockthe trigger assembly 19 out and the font locking pins 31, 31 in duringthe printing cycle. For example, when the print button 28 is depressed,the trigger stem 20 and connection 21 are moved downwardly causing themember 18 to pivot about its pivot 22 to release the latch 24 from thecatch 16. Simultaneously, the downward movement of the stem 20 causesthe washer 32 to engage and pivot the bracket 29 about the pivot 30,thereby causing upward movement of the pins 31, 31 into the notches 35and the activation of the switch 40 (FIG. 4) to commence the printingcycle. Activation of the switch 40 in turn causes activation of themotor to rotate the clutch 11 and the cam assembly 14 in a clockwisedirection as indicated. As the cam assembly l4 and thus the cam surface50 rotate, the outer surface 50 engages the portion 51 of the member 18to keep the trigger assembly 19 and latch 24 open and the pins 31, 31locked into the notches 35 (FIG. 11). When the cam assembly 14 hasrotated sufficiently so that the partial cylindrical surface 50 passesthe point 51, the member 18 is caused to move in a clockwise directionas a result of the force exerted on the member 34 by the springs 38, 38which in turn causes the latch 24 to engage the catch 16 to preventfurther movement of the clutch and the cam assembly 14. It should benoted that the clutch 15, in addition to including means to limit themovement of the assembly 14 to a single revolution, also includes aninternal spring means for braking the assembly 14 to prevent a suddenstop when the latch 24 engages the catch 16.

With general reference to FIG. 3 and specific reference to FIG. 4, aprint media or image carrier in the form of the printing tape 52 is fedfrom the roll of tape 54, through the means for advancing the media andpast the printing station 55. As illustrated, the printing station 55 islocated immediately above the piston assembly 49 to enable the printingof a desired character onto the tape 52 through the cooperative actionof the piston assembly 49 and the font 36 in the manner hereinafterdescribed. The roll of printing tape 54 is rotatably mounted on thecenter spindle 56 of a cartridge 58 supported within the frame of theapparatus to allow the tape 52 to be freely taken from the roll 54.

The means for advancing the print media 52 includes a double crank leveror motion transfer arm 59 rotatably supported with respect to theapparatus frame by the shaft 60. One arm of the transfer lever 59 servesto rotatably support a roller 61 adapted for rolling engagement with thecam surface 42. A second arm of the lever 59 is anchored via the springmember 62 to the apparatus frame thereby causing the member 59 to becontinuously biased in a clockwise direction and the roller 61 biasedtoward engagement with the surface 42. The third arm of the transferlever 59 is connected via the connecting member 64 to one arm of abellcrank member 65. The connecting member 64 extends through the end ofthe third arm of the lever 59 and into an elongated slot 66 formed inthe bellcrank to transfer movement from the lever 59 to the bellcrank65. The bellcrank 65 is secured to a spring clutch 69 which in turn ismounted to a shaft 68 in a manner which permits free rotational movementof the clutch 69 and thus the bellcrank 65 about the shaft 68 in aclockwise direction, but which grips the shaft 68 and causes the clutch69, the bellcrank 65 and the shaft 68 to rotate in unison when thebellcrank 65 is moved in a counterclockwise direction.

As shown best in FIG. 6, a drive roller 70 is mounted to the shaft 68for rotational movement therewith and an idler roller 71 is disposedimmediately above the drive roller 70 in sufficient proximity thereto tocause the image carrier 52 passing between the rollers 70 and 71 to movein the direction indicated upon counterclockwise movement of the driveroller 70. A rubber O ring 72 is disposed in a groove on the peripheryof the roller 70 to aid in gripping the print media 52 and advancing it.A letter spacing arm 74 is connected to a second arm of the bellcrank 65for variably advancing the media 52 during the printing cycle. Asillustrated, the spacing arm 74 has a forwardly extending portion 75adapted for engagement with a notch 76 formed in the letter spacing ring77 (FIG. 12) of the font 36 to limit the counterclockwise movement ofthe bellcrank 65 and thus similar movement of the drive roller 70.

This in turn limits the advancement of the image carrier 52 during eachprinting cycle. This arrangement provides means for variably advancingthe media 52 in accordance with the particular character being printed.For example, as shown in FIG. 12, the underside of the font 36 includesa letter spacing ring 77 having a plurality of notches 76 of differentsize for controlling the image carrier advance following the printing ofeach character. It should be noted that the particular size of the notch76 and thus the permissible forward movement of the spacing arm 74during the printing of any particular character will depend upon thecharacter being printed. For example, the size of notch 76 associatedwith each of the letters I and W will be different since the letter 1takes less printing space than the letter W and consequently, theadvance of media following the printing of the I would be less. Thus,the notch 76 for the letter I is such that it allows less forward movement of the arm 74 than that for the letter W thus advancing the printmedia a lesser amount. Thus, the

button 28, the latch 24 is releasedfrom the catch 16.

and the cam assembly 14 is rotatedin a clockwise direction by the motor10. Because of the tension in the spring member 62, the roller 61 iscaused to roll along the surface 42 during rotation of the cam assembly14.

As the assembly 14 begins to rotate, the shape of the surface 42 is suchthat it causes movement of the lever 59 in a counterclockwise direction,corresponding clockwise movement of the bellcrank 65 and rearwardmovement of the letter spacing arm 74. During this movement, the shaft68 and drive wheel 70 do not rotate because of the orientation of theclutch 69 with respect to the shaft 68. It should be noted that duringthis portion of the printing cycle, the radial distance between theshaft 12 and the point on the surface 41 engaged by the roller 61 isincreasing or remaining constant. If this condition is not met, themedia 52 would begin to advance prior to the printing portion of theprinting cycle. At a preselected point during the printing cycle, thepiston assembly 49 is released and the image of the character beingprinted is transferred to the media 52. Following this, the surface 42at the point engaged by the roller 61 is such that the radial distancebetween the shaft 12 and this point is decreasing, thereby allowing forclockwise movement of the lever 59, counterclockwise movement of thebellcrank 65 and forward movement of the spacing arm 74 into engagementwith the notch 76. This movement also causes counterclockwise movementof the shaft 68 and drive wheel 70 and advancement of the print media52. Although the surface 42 may have several operable alternativeshapes, it is necessary that the radial distance between the portion ofthe surface 42 engaged by the roller 61 and the shaft 12 prior to orduring the printing step never be decreasing since this would causeadvancement of the print media 52 before or during the printing step,thus resulting in an inferior or improperly spaced printed character.

As further illustrated in FIG. 3, means is provided in the form of theeccentric shaft 53 for adjusting the spacing between adjacent printedcharacters. As is evident from FIGS. 3 and 4 and from the description ofthe means for advancing the image carrier the distance which the imagecarrier 52 is advanced between printed characters is dependent on, amongother things, the position of the axis 60 about which the member 59rotates relative to the surface 42. For example, the greater thedistance which the axis 60 is spaced from the surface 42, the smallerthe counter clockwise movement during revolution of the assembly 14, andthus, the smaller the advancement of the media 52. Similarly,positioning the axis 60 closer to the surface 42 would result in agreater rotational movement of the member 59 during a printing cycle andthus greater advancement of the media. Because of the eccentric shaft53, one end of which supports the member 59 and the other end of whichis supported by the apparatus frame, the position of the axis 60 aboutwhich the member 59 rotates relative to the cam surface 42 can be variedby rotation of the shaft 53. As pointed out above, this in turn variesthe advancement of the media between adjacent characters. Rotation ofthe shaft 53 is accomplished by manual rotation, of a letter spacingselector wheel 63 which is operatively connected to the shaft 53 via aplurality of gears 57a and 57b.

Associated with the shaft 68 as shown in FIG. 3 is a means for advancingthe image carrier 52 (FIG. 4) to provide proper spacing between printedwords. Such means includes a word space lever 78 freely pivotable at oneend about the shaft 68 and moveable at its other end between a stopmember 79 and one end of a lever arm 80. The arm 80 is pivotallyconnected at its other end 81 to the frame of the apparatus and isconnected between its ends to a word space button 82 operativelydisposed in the apparatus frame. Although not specifically illustratedin the drawings, the lever arm 80 has a shoulder portion adapted toengage a portion 84 of a directional clutch 85 to rotate the clutch 85in a counterclockwise direction upon depression of the word space button82. The clutch 85 is a conventional directional clutch mounted on theshaft 68 in a manner which causes the clutch 85 to be freely rotatedabout the shaft 68 in a clockwise direction, but which grips the shaft68 and rotates it therewith when the clutch 85 is moved in acounterclockwise direction. Thus, depression of the button 82 andconsequential downward movement of the arm 78 and counterclockwisemovement of the clutch 85 causes counterclockwise rotation of the shaft68 and drive wheel 70, thereby advancing the print media. As can beseen, the distance which the media 52 is advanced is directly dependentupon the permissible downward movement of the arm 78 against thevertical stop 79. In this respect, means which will be discussed lateris provided for automatically adjusting the vertical position of thestop 79 in relation to the size of the characters being printed, therebyproviding the proper word spacing for the various sizes of characters.

Also associated with the shaft 68 and the clutch 85 as illustrated inFIG. 3 is a means for feeding the print media 52 (FIG. 4) when arelatively large advancement of the media is desired such as, forexample, when the printing or a particular group of words has beencompleted and the media is desired to be advanced for cutting andremoval from the apparatus. This means includes a cammed gear segment 86pivotally connected at the pivot 88 to the apparatus frame and having aplurality of gear teeth 89 adapted to operatively engage correspondinggear teeth 90 formed in the clutch 85. Disposed against a lower portionof the gear segment 86 is one end of a spacing linkage 81 which ispivotally mounted to the frame at the pivot 92 and which is connected atits other end to a tape feed button 94. Upon depression of the button94, the linkage 91 moves about the pivot 92 causing upward movement ofthe segment 86 and corresponding counterclockwise movement of the clutch85. As discussed earlier, such movement of the clutch 85 also causescounterclockwise movement of the shaft 68 and drive wheel 70 andadvancement of the print media 52. A spring member 97 is attached to thegear segment as shown to bias the segment 86 downwardly and againstdepression of the button 94. This also biases the clutch 85 in aclockwise direction against the shoulder of the arm 78 (not shown) andthus biases the arm 78 upwardly against the end of the arm 80.

Referring again to FIG. 3 and also to FIG. 5, the color carrier orribbon 96 is fed from a ribbon cartridge 98 of conventional design, pastthe printing station 55 above and at right angles to the print media 52,through the means for advancing the ribbon and finally onto a take-upspool 99. Although not specifically illustrated, the take-up spool 99 ispowered by a conventional stalled synch-motor such as Model No.GL33RA-46 supplied by Hansen Manufacturing Company of Princeton,Indiana.

The means for advancing the ribbon 96 during the printing cycle includesa ribbon advance arm assembly 100 pivotally mounted to the apparatusframe at the pivot 101 and having a pair of arms 102 and 104 integrallyformed with and extending outwardly therefrom. A roller 105 is rotatablysupported by the end of the arm 102 for engagement with the cam surface45 of the cam assembly 14. As illustrated, the surface 45 is such thatrotation of the assembly 14 causes reciprocating movement of the arm 100about the pivot 101 as a result of engagement between the surface 45 andthe roller 105. The end of the arm 104 is operatively connected to aclutch arm 106 by an appropriate connection member 108 for transferringthe reciprocating movement of the arm 100 to the arm 106. Also connectedwith the arm 104 is a spring member 107 biasing the entire advance armassembly 100 in a counterclockwise direction about the pivot 101.integrally formed with the clutch arm 106 is a conventional directionalclutch 109 similar to the clutch 85 used in the tape advance means(FIGS. 3 and 4). The clutch 109 is mounted to a shaft 110 in a mannersuch that it is freely movable relative to the shaft 110 when moved in acounterclockwise direction, but such that it grips the, shaft 110 androtates it and the ribbon drive wheel 11 1 therewith when it is moved ina clockwise direction. Similar to the drive wheel 70, the drive wheel111 includes an ring 112 disposed in a groove about its periphery which,together with the roller 114, causes the ribbon 96 to be moved in thedirection shown in re sponse to clockwise movement of the wheel 11 1.When the printing cycle is commenced, the shape of the surface 45 issuch that its engagement with the roller 105 causes clockwise movementof the arm 100 about the pivot 101. During this movement, the clutch 109and the clutch arm 106 are moved in a counterclockwise direction.Following release of the piston, the shape of the portion of the surface45 engaging the roller 105 is such that it allows the arm 100 to move ina counterclockwise direction because of the spring 107, thereby causingclockwise rotation of the wheel 111 and advancement of the ribbon 96.Similar to the cam surface 42, the surface 45 may have several operativealternative shapes. However, it is necessary that the surface 45 be suchthat before and during the release of the piston, the arm is precludedfrom movement in a counterclockwise direction. If such condition is notmet, the ribbon 96 will be advanced during the actual printing step,thereby resulting in an inferior printed character and possible damageto the ribbon 96. It should also be noted that, for optimum performance,the shape of the surfaces 42 and 4S and their relation to theirrespective operative elements be such that the ribbon is advancedslightly ahead of the print media. Since the ribbon 96 is quite flimsycompared to the image carrier 52 (FIG. 4), movement of the media priorto the ribbon would cause the ribbon to ruffle, thereby resulting in asmudge on the tape. When the ribbon is moved first, however, the tensionin the ribbon results in a free break away from the tape. it should benoted that the image carrier or media 52 (FIG. 4) is an adhesive backedprinting media of relatively stiff construction which is capable ofreceiving an image from the color carrier 96 (FIG. when the same aredisposed between the raised character of the font and the pistonassembly and when the piston head of the piston assembly is propelledtoward the raised character as hereinafter described.

Extending outwardly from the upper end of the arm is a pin 116 adaptedfor engagement with a canted stop member 118 to limit thecounterclockwise movement of the arm 100 and thus the advancement of theribbon 95. The stop member 118 forms the upper portion of a ribbonadvance adjustment slide 119 which is slideably connected relative tothe apparatus frame and which is biased downwardly by the spring member121 connected between the frame and the slide 119. As illustrated, theslide 119 contains an elongated opening which, together with the ribbonspacing adjustment bar 122, enables adjustment of the vertical positionof the slide 119. This adjustment, in turn, controls the extent to whichforward, counterclockwise movement of the ribbon advance arm 100 ispermitted. As is evident from the drawings, downward adjustment of theslide 119 permits further counterclockwise movement of the arm 100,while upward adjustment of the slide 119 reduces such permissiblemovement. The stop member 79 which limits the downward pivotal movementof the word space arm 78 is connected with the upper portion of theslide 119. Thus, adjustment of the vertical position of the slide 119also adjusts the vertical position of the stop 79 to thereby vary theadvancement of the media upon depression of the word space button 82.

As shown best in FIG. 3, the adjustment bar 122 is an elongated memberhaving one end extending through the opening 120 in the slide 119 andhaving its other end operatively associated with a font size selectorwheel 124. The wheel 124 is mounted on a shaft 125 which is joumaled ateach end by appropriate means to the apparatus frame. A gear 126 islikewise mounted to the shaft 125 and contains a plurality of gear teethadapted for engagement with corresponding gear teeth in a rack 128integrally formed with the adjustment bar 122. Through this arrangement,rotation of the wheel 124, and thus the shaft 125 and the gear 126,causes lateral movement of the bar 122. It should be noted that the bar122 is slideably mounted relative to the apparatus frame by appropriatemeans to permit such movement.

The end of the bar 122 which extends through the opening 120 includes agenerally inclined surface having a plurality of steps or intermediatelevels 129 innature of the end of the bar 122, the vertical position ofthe slide 119 will depend upon the lateral position of the bar 122. Forexample, if the bar 122 is moved toward the left as viewed in FIG. 3resulting from a clockwise movement of the wheel 124, the slide 119 willbe moved upwardly as a result of engagement between the upper end of theopening 120 and the inclined surface at the end of the bar 122. Thesteps 129 in the inclined surface enable definite vertical positions ofthe slide to be achieved in response to a particular-setting of thewheel 124. As discussed above, such vertical adjustment of the slide 119controls the extent of ribbon advance and the word space advance of theprint media during each printing cycle. The wheel 124 includes variousnumerical settings corresponding to the various sizes of charactersnormally printed thereby enabling the operator to properly set theselector wheel to achieve the correct ribbon advance and word spaceadjustments.

Referring next again to FIG. 3 and also to FIG. 7, a means adapted tocompensate for letter interlocking is indicated generally by thereference numeral 130. In the present application, the term letterinterlocking refers to the ability of certain combinations of adjacentletters to fit together or interlock because of their particular shape.Because of such interlocking, a space adjustment is required to makesuch combinations visually satisfactory. For example. if the letters Aand V or the letters A and W were printed adjacent to each other withoutany such adjustment, the space between such letters would appear to begreater than that between other letters because of the particular shapeof such letters. To compensate for this, a means 130 is provided forphysically moving the image carrier 52 (FIG. 4) backward an appropriateamount to compensate for the apparent difference in spacing.

More specifically, as shown best in FIG. 7, the means 130 includes afirst elongated member 131 pivotally connected near its lower end to theapparatus frame at the pivot 132. The upper end of the member 131 isconnected to the apparatus frame by the floating pivot 134 which permitslimited rotational movement of the member 131 about the pivot 132. Asecond elongated member or linkage 135 is pivotally connected at one endof the member 131 by the pivot 134 and is connected at its other end toan intermediate portion of the member 131 by a connecting pin 136 in amanner permitting limited pivotal movement of the link 135 relative tothe member 131 about the pivot 134. The limitation of such movement isaccomplished by an elongated slot indicated by the broken line 138 inthe member 131. The upper end of each of the members 131 and 135 haveintegrally connected thereto. a print media guide 139 and 140respectively, each of which are designed to guide the advancement of themedia 52. Further, when a letter interlocking adjustment is necessary,the guides 139 and 140 are adapted to grip the media 52 and move it tothe right as viewed in FIG. 7 to compensate for such letterinterlocking.

Associated with the members 131 and 135 is a means for causing movementof said members in the form of a letter interlock slide 141 which isslideably connected to the apparatus frame by appropriate slide meansand which is connected for vertical, reciprocal movement in response tothe depression and release of a letter interlock button 142. Themovement of the button 142 is transferred to the slide 141 via theconnecting link 144 pivotally connected to the apparatus frame at thepivot 145. The slide 141 includes an elongated, diagonally disposed slot146 through which the pin 136 extends with the slot being disposed suchthat vertical movement of the slide 141 causes pivotal movement of themember 135 about the pivot 134. Upon upward movement of the slide 141,the link 135 is moved in a counterclockwise direction about the pivot134 relative to the member 131 as a result of the pin 136 being guidedand urged to the right by the lower side of the diagonal slot 146.During this relative rotational movement between the members 131 and135, the guide 140 is moved upwardly toward the guide 139 until themedia 52 is nipped by a portion 148 of the guide 140 and is grippedbetween the portion 148 and the guide 139. When this is accomplished,the rotated position of the link 135 is such that further upwardmovement of the slide 141 causes engagement between the pin 136 and theright hand end of the slot 138 to thereby result in clockwise rotationof the member 131 about its pivot 132. During this latter movement ofthe member 131, the media 52, which has been gripped between the portion148 and the guide 139. is moved toward the right, thereby affordingproper spacing between those certain letter combinations for whichadjustment is necessary. It should be noted that the letter interlockingadjustment is made subsequent to the printing of the first letter ofthose various combinations of letters and prior to the second. Forexample. when printing the letters AV, the button 142 is depressed andadjustment is made after the letter A is printed and prior to theprinting of the letter V.

It can be seen that the extent to which the media 52 is physically movedto the right is dependent upon the extent to which the slide 141 ismoved upwardly. This, in turn, is dependent upon the extent to which thebutton 142 is moved downwardly. As illustrated best in FIG. 3, thepermissible downward movement of the button 142 is dependent upon thelateral position of an adjustment slide 149. The slide 149 is slideablyconnected to the apparatus frame by appropriate means and includes aninclined surface at one end with a plurality of steps or levels 150adapted for engagement with the link 144 and serving to limit thepivotal movement of the link 144 about its pivot 145. The slide 149 iskeyed to the rotation of the font size selector wheel 124 by a rack 151integrally formed with the slide 145 and a corresponding gear 152secured to the shaft 125. Upon rotation of the selector wheel 124, thelateral position of the slide 149 and thus the permissible rotationalmovement of the link 144 and I the extent to which the media 52 (FIG.11) is moved rearwardly is adjusted. Because the ribbon advance and theword space adjustments are also controlled by adjustment of the wheel124, the various operative elements by which each of the ribbon advance.the word space and the letter interlocking is controlled, areconstructed such that for a particular character size setting of thewheel 124, the proper spacings and advancements for such character sizewill be achieved.

Referring generally again to FIG. 3 and more specifically to FIGS. 4, 5,14 and 15, a piston assembly 49 is positioned immediately below theprinting station 55 and comprises a cylindrical body 154 housing apiston head 155 mounted to one end of a piston stem 158 and a springmember 156 biasing the piston head 155 upwardly. As best illustrated inFIGS. 14 and 15, the piston stem 158 extends through and below thecylindrical member 154 and includes a portion 159 at its lower end towhich a roller 160 is rotatably mounted. The roller 160 is designed forrolling engagement with the internal cam surface 48 shown best in FIGS.14 and 9.

One end of the spring 156 is disposed against the bottom surface of thepiston head 155 and the other end is supported by a spring retainingmember or cup 162 positioned immediately below the spring 156. The cup162 is supported at its lower end by a spring lifter 165. During theprinting cycle, the stem 158 and piston head 155 are caused to movedownwardly in opposition to the force of the spring 156 as a result ofengagement between the roller 160 and the cam surface 48. When therotation of the cam assembly 14 is such that the roller 160 reaches thepoint 164 of the surface 48 (FIG. 9), the roller 160 is released and thespring 156 which has been compressed during downward movement of thehead 155 expands, propelling the piston head 155 upwardly toward theraised characters on the underside of the font 36 thereby transferringthe image of the raised character from the color carrier 96 to the imagecarrier 52 disposed immediately below they raised character. When thisis accomplished, the printing step is complete and the piston assemblyelements return to the position illustrated in FIG. 14. As shown inFIGS. 14 and 15, the color carrier 96 and the image carrier 52 cross atright angles to each other immediately below the raised character 27which is aligned with the printing head 155. It should be noted that theimage carrier 52 is disposed below the color carrier 96. Although theprinting head 155 may be composed of a variety of materials, it isimportant that such material have a good memory so that impressions ofpreviously printed characters do not remain in the head and that thematerial be softer than the material from which the raised characters onthe font are composed to reduce wear on the font. It should also benoted that a font retainer 9 is slideably mounted to the frame of theapparatus with a portion extending over the periphery of the font 36 tooppose and prevent upward movement of the font 36 as a result of thepiston head 155 being propelled toward the font and as a result of thealignment pins 31, 31 (FIG. 11) being moved upwardly into the notches35.

Associated with the piston assembly 49 is a means for varying thevertical position of the retaining cup 162 and thus the base againstwhich the spring member 156 rests. As will be discussed below, this alsovaries the upward force of the spring 156 on the piston head 155 whenthe piston roller 160 has been released from the surface 48 and thus theforce with which the head 155 is propelled toward the raised characters27 of the font 36. In general, such a means is designed to vary theforce urging the head 155 toward the font 36 in proportion to the sizeor area of the character being printed. Thus a period or a comma wouldbe printed with less force than, for example, the letters M or W. Suchmeans is necessary to achieve uniform printing of the variouscharacters.

The means for varying the printing pressure exerted by the piston head155 on the raised characters 27 on the font 36 includes a spring lifter165 having one end integrally connected to a rack 166, and having itsother end extending through an elongated opening 168 in the cylindermember 154 and engaging a lower portion of the retaining cup 162. Withthis arrangement, the vertical position of the cup 162 is dependent uponthe vertical movement of the lifter 165. Associated with the rack 166and having teeth adapted for engagement with corresponding teeth on therack 166 is a gear 169 whose rotational movement causes verticalmovement of the rack 166 and the lifter 165. With reference to FIG. 3,the gear 169 is mounted to one end of a shaft 170 whose other end isconnected to a gear 171. The shaft 170 is supported by appropriate meansto the apparatus frame. The gear 171 is operatively connected via anintermediate gear 172 to a rack 174 mounted for sliding movement byappropriate slides -to the apparament with the pin 175 for limiting thelateral movement thereof. This controlled lateral movement of the pin175, as a result of the corresponding operation of the racks 174 and 166and the gears 172, 171 and 169, controls the vertical position of thecup 162 and thus the force with which the head 155 is propelled upwardlytoward the font 36 during the printing cycle. For example, referring toFIGS. 14 and 15, if the vertical position of the cup 162 is near thebottom of the cylindrical member 154, the force by the spring 156propelling the piston head 155 upwardly when the roller 160 is releasedfrom the surface 48 is much less than if the vertical position of thelifter 162 is higher since the spring 156 would not be compressed asmuch. It should be noted that the portion 178 (FIG. 8) corresponds tothe pressure control ring 177 (FIG. 12) disposed on the underside of thefont 36 whose particular shape and orientation relative to thecharacters on the font is such that the movement of the pin 175 againstthe portion 178 as shown in FIG. 8 provides for the proper verticalpositioning of the cup 162, and thus the proper printing pressurerelative to the size or area of the character being printed. It shouldbe noted that this means varies the printing force so that it isgenerally in proportion to the size of the character printing. Ideally,the force would vary in direct proportion to the square area of thecharacter printed.

With general reference now to FIG. 3 and more specific reference to theother figures, the general operation of the lettering apparatus of thepresent invention may be understood as follows: First, as illustrated inFIGS. 1 and 2, the font 36 is manually rotated about its center supportshaft 13 until the character desired to be printed is positioned inalignment with the printing station 55. Although exact alignment of thecharacter with the printing station through this manual rotation is notnecessary, it is necessary that the character be sufficiently aligned sothat the font locking pins 31, 31 will engage the tapered notches 35 asshown in FIG. 11. After the desired character is so aligned, the printbutton 28 is depressed causing the member 18 to pivot about the point 22releasing the catch 16 and causing the font locking pins 31, 31 to bemoved upwardly toward engagement with the tapered notches 35 (FIG. 11)on the underside of the font 36. When the pins 31, 31 are fully extendedinto the notches 35, the motor 10 is activated, causing the cam assembly14 to rotate about the shaft 12. Such activation of the motor 10constitutes the commencement of the printing cycle. During the initialportion of the printing cycle, the surface 42 engages the roller 61 in amanner which causes counterclockwise movement of the member 59 about itsaxis 60. This movement, in turn, causes clockwise movement of thebellcrank member about the shaft 68. During this same initial portion ofthe printing cycle, the surface 45 engages the roller to pivot theassembly 100 in a clockwise direction above the pivot 101. Asillustrated, this movement causes corresponding counterclockwisemovement of the arm 106 and the clutch 109. Also, during this initialportion of the printing cycle, the surface 48, best illustrated in FIGS.9 and 14, engages the roller 160 attached to the end of the piston stem158. As the cam assembly 14 and thus the surface 48 rotate, theengagement between the surface 48 and the roller 160 causes downwardmovement of the printing head and compression of the spring '156.

When the cam assembly 14 has rotated to the point at which the roller160 reaches the point 164 of the surface 48 (FIG. 9), the pistonassembly is released, causing the piston head 155, as a result of thespring 156, to be propelled upwardly toward the raised character on theunderside of the font 36. Because the image carrier and the colorcarrier are disposed immediately below the raised character, an image ofthe raised character is transferred from the color carrier to the imagecarrier. The propelling of the piston head 155 toward the font 36 isreferred to as the printing step. Following the printing step, theelements of the piston assembly 49 return to the position illustrated inFIG. 14. Also, following the printing step, the surfaces 42 and 45 ofthe cam assembly 14 are such that clockwise movement of the member 59and counterclockwise movement of the assembly 100 are permitted. Thesemovements, in turn, permit counterclockwise movement of the tape drivewheel 70 and clockwise movement of the ribbon drive wheel 111respectively. As described above, the movement of the wheels 70 and Illcause appropriate advancement of the image carrier and the color carrierso that the image carrier and color carrier are appropriately positionedfor the next printing cycle.

As also described in the above specification, the preferred embodimentof the printing apparatus of the present invention includes a means forvariably spacing the characters being printed in accordance with thespace needed to print such characters, a means for backspacing the imagecarrier a specified amount to compensate for the interlocking of certainletter combinations, and a means for varying the force with which thepiston head 155 is propelled against the raised character on theunderside of the font in direct proportion to the square area of thecharacter being printed. Finally, means are also provided for advancingthe image carrier to provide proper spacing between words and a meansfor adjusting the above features and elements to provide for properspacings, advancements and backspacing in accordance with the particularsize of characters being printed.

Although the description of preferred embodiment of the presentinvention has been quite specific, it is contemplated that variousmodifications may be made to the embodiment disclosed without deviatingfrom the spirit of the present invention. Consequently, the scope of thepresent invention is intended to be dictated by the appended claims,rather than by the description of the preferred embodiment.

I claim:

1. A printing apparatus having means for providing proper spacingbetween the printed characters of cer tain two character combinationswhose spacing appears visually improper because of the comparative shapeof such characters when positioned adjacent to each other comprising:

a printing station;

an image carrier;

a font having a plurality of raised characters, each selectivelypositionable in alignment with said printing station to thereby definean aligned character;

means for causing an image of said aligned character to be transferredto said image carrier;

means for guiding said image carrier between said aligned character andsaid printing station and for advancing said image carrier relative tosaid printing station subsequent to each transfer of an image of saidaligned character to said image carrier; backspace means for causing theselective rearward movement of said image carrier a specified distancerelative to said printing station, such rearward movement occurringsubsequent to the printing of the first character of certain twocharacter combinations and prior to the printing of the second characterof such two character combinations and said specified distancecorresponding to the distance necessary to provide proper spacingbetween the characters of said certain two character combinations.

2. The printing apparatus of claim 1 wherein said backspace meansincludes first and second elongated members pivotally connected to eachother at one end for limited relative pivotal movement, each of saidfirst and second elongated members including means for gripping saidimage carrier upon said limited relative pivotal movement.

3. The printing apparatus of claim 2 wherein the connection between saidfirst and second elongated members is such that subsequent to saidlimited relative pivotal movement, further movement of said first andsecond elongated members results in corresponding movement of said imagecarrier.

4. The printing apparatus of claim 3 having means for moving said firstand second elongated members.

5. The printing apparatus of claim 4 wherein said means for moving saidfirst and second elongated members includes a slide member adapted forreciprocal movement and having an elongated slot transversely disposedwith respect to the direction of reciprocal movement of said slidemember.

6. The printing apparatus of claim 5 wherein said means for moving saidfirst and second elongated members includes a pin connected with saidfirst and second elongated members and extending through said elongatedslot.

7. The printing apparatus of claim 6 wherein said pin is securelyfastened to one of said first and second elongated members andassociated with the other for limited movement relative thereto.

8. The printing apparatus of claim 7 having means for limiting themovement of said first and second elongated members, the extent to whichsaid movement is limited being dependent upon the size of the characterson said font.

1. A printing apparatus having means for providing proper spacing between the printed characters of certain two character combinations whose spacing appears visually improper because of the comparative shape of such characters when positioned adjacent to each other comprising: a printing station; an image carrier; a font having a plurality of raised characters, each selectively positionable in alignment with said printing station to thereby define an aligned character; means for causing an image of said aligned character to be transferred to said image carrier; means for guiding said image carrier between said aligned character and said printing station and for advancing said image carrier relative to said printing station subsequent to each transfer of an image of said aligned character to said image carrier; backspace means for causing the selective rearward movement of said image carrier a specified distance relative to said printing station, such rearward movement occurring subsequent to the printing of the first character of certain two character combinations and prior to the printing of the second character of such two character combinations and said specified distance corresponding to the distance necessary to provide proper spacing between the characters of said certain two character combinations.
 2. The printing apparatus of claim 1 wherein said backspace means includes first and second elongated members pivotally connected to each other at one end for limited relative pivotal movement, each of said first and second elongated members including means for gripping said image carrier upon said limited relative pivotal movement.
 3. The printing apparatus of claim 2 wherein the connection between said first and second elongated members is such that subsequent to said limited relative pivotal movement, further movement of said first and second elongated members results in corresponding movement of said image carrier.
 4. The printing apparatus of claim 3 having means for moving said first and second elongated members.
 5. The printing apparatus of claim 4 wherein said means for moving said first and second elongated members includes a slide member adapted for reciprocal movement and having an elongated slot transversely disposed with respect to the direction of reciprocal movement of said slide member.
 6. The printing apparatus of claim 5 wherein said means for moving said first and second elongated members includes a pin connected with said first and second elongated members and extending through said elongated slot.
 7. The printing apparatus of claim 6 wherein said pin is securely fastened to one of said first and second elongated members and associated with the other for limited movement relative thereto.
 8. The printing apparatus of claim 7 having means for limiting the movement of said first and second elongated members, the extent to which said movement is limited being dependent upon the size of the characters on said font. 